Ballasts are an integral part of many gas discharge systems such as fluorescent or high intensity density discharge (HID) lighting. Ballasts are used to regulate the flow of electrical current to an illuminating element (also denoted herein as lighting element or lamp) to generate and maintain electromagnetic illumination (also denoted herein as illumination or light).
Fluorescent ballasts are commonly used in office lighting, and compact fluorescent lamps with integrated ballasts are widely used for domestic lighting. HID lighting systems, on the other hand, are typically used for lighting in larger facilities such as large retail stores, industrial buildings, and studios. HID lighting is also commonly used in parking lots and for street lighting. HID systems can consist of metal halide (MH) lighting systems as well as high pressure sodium (HPS) lighting systems.
Traditional fluorescent lighting incorporates electromagnetic adaptors or ballasts to power the lamp. Standard electromagnetic HID ballasts utilize a basic low frequency iron core transformer, a capacitor, and in the case of high pressure sodium lighting systems an additional igniter. These components ignite and maintain the lamp in a desired operating state, supplying the required power in an appropriate form.
However, electromagnetic ballasts exhibit a number of disadvantages including: poor energy efficiency; susceptibility to incoming voltage fluctuations; hard initial start up which degrades the life expectancy of the lamp; general inability to be dimmed; large weight making them difficult to install in above ground locations; many wires to interconnect which complicates installation; audible noise production as the device ages; relatively high operating temperatures; potential for damage by power surges; as well as other disadvantages.